جستجوی مقالات مرتبط با کلیدواژه « Congo red » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

The objective of this work was to evaluate the efficiency of a promising ultrasonically assisted adsorption with the Fe3O4@THAM-CH2CH2Cl magnetic nanoparticle (MNPS) as a new adsorbent for the elimination of Congo red from water samples. The FE-SEM images show that Fe3O4@THAM-CH2CH2Cl MNPs adsorbent is spherical. Due to the presence of pores on the Fe3O4@THAM-CH2CH2Cl MNPs adsorbent surface, the proposed adsorbent can remove Congo red from the aqueous environment by trapping the pollutant in its pores. Different parameters influencing the ultrasonically assisted adsorption (UAA) by the Fe3O4@THAM-CH2CH2Cl MNPs adsorbent, including the dye concentration and adsorbent mass, ultrasonic time, and pH, were studied and optimized by multivariate methods. The best adsorption efficiency was obtained at 0.04 g of adsorbent, 17 mg.L-1 of dye, pH = 6.6, and ultrasonic treatment for 7.2 min. The results indicated that the efficiency of dye adsorption ranged from 97.85 to 99.65 %. The kinetic, isotherm, and thermodynamic for the proposed method were assayed. The larger R2 for the pseudo-second kinetic model indicates that this model is more suitable to describe the adsorption process of Congo red on the Fe3O4@THAM-CH2CH2Cl MNPs adsorbent. The Langmuir adsorption isotherm had a larger correlation coefficient (R2 = 0.9987), which indicates it fits best with the experimental data and is more suitable for the Congo red adsorption process. Analysis of actual samples showed that Congo red removal values (R %, mean ± standard deviation, n = 3) in tap water and wastewater were 98.48 ± 1.52 % and 98.05 ± 2.11 %, respectively.

Raw bentonite (RB), a known low-cost versatile clay was used as an adsorbent. RB was treated thermally and chemically to increase its adsorption capacity. For thermal treatment (TTB), the bentonite was heated at 400 °C for 60 min, and for the chemical modification, its surface was treated by cetyltrimethylammonium bromide (CTAB) to prepare organo-modified bentonite (CTAB-B). The removal of Congo red dye (CR) from aqueous solution was investigated in the batch mode. The prepared adsorbents were characterized by SEM, BET, and FTIR analyses. The effects of various experimental parameters such as contact time, pH, adsorbent dosage, dye concentration and temperature were investigated. The obtained results were in good agreement with the Langmuir isotherm model, and the maximum adsorption capacity of RB, TTB and CTAB-B was 43.1, 55.86 and 116.28 mg/g, respectively. The adsorption kinetic was better described by the pseudo-second order kinetic model. The results showed that thermally or chemically modified bentonite could be proposed as a low-cost adsorbent for the removal of CR from water.

In this study، tea waste (TW) is employed for the removal of Congo red (CR) from aqueous solutions in a fixed-bed column at 30 °C. The breakthrough curves of the adsorption process of CR on TW at three different flow rates are determined. The results revealed that the breakthrough curves were dependent on flow rates in a manner in which a lower flow rate was in favor of the CR adsorption in the column-mode process. As the flow rate increased from 4. 6 to 6. 6 mL/min، the amount of dye uptake capacity decreased from 1. 78 to 1. 53 mg/g. The effect of the presence of Fe2O3 on the adsorption of CR on TW is also studied at 30 °C. The results showed that the presence of nanoparticles increased the adsorption uptake of CR by about 32%. Moreover، four novel models are developed for the prediction of the breakthrough curves resulted from the experimental data. The results of the models were in good agreement with experimental data (R2>0. 99). The statistical parameters confirm the suitability of the models.

1 Center for Separation Processes Modeling and Nano-Computations، School of Chemical Engineering، College of Engineering، University of Tehran، P. O. Box 11365-4563، Tehran، Iran2 Oil and Gas Center of Excellence، University of Tehran، Tehran، IranABSTRACTIn this work، the adsorption of the anionic dye، Congo red (CR)، from aqueous solution by using tea waste (TW) has been carried out at 30 °C. The equilibrium sorption isotherms and kinetics were investigated. The equilibrium adsorption was studied by the Langmuir and Freundlich models of adsorption. The experimental results manifested that the Langmuir isotherm was the best model for the adsorption of CR by TW and implied the monolayer adsorption of CR on TW with the adsorption capacity of 40. 6 mg/g at 30 °C. The kinetic data resulted from batch experiments were analyzed using pseudo-first-order and pseudo-second-order models. It was found that pseudo-second-order model provided the best fit for the experimental data (R2>0. 99). The results illustrated that both silica and Fe2O3 nanoparticles increased the adsorption of CR on TW by about 5% and 10% at 30 °C، respectively. The results suggested that TW should be a potential low-cost adsorbent for the removal of CR from aqueous solution.